• Journal of the Earthquake Engineering Society of Korea
• /
• v.2 no.1
• /
• pp.79-93
• /
• 1998

The eigenvalue problem is presented for the building with added viscoelastic dampers by using component mode method. The Lagrange multiplier formulation is used to derive the eigenvalue problem which is expressed with the natural frequencies of the building, the mode components at which the dampers are added, and the viscoelastic property of the damper. The derived eigenvalue problem has a nonstandard form for determining the eigenvalues. Therefore, the problem is examined by the graphical depiction to give new insight into the eigenvalues for the building with added viscoelastic dampers. Using the present approach the exact eigenvalues can be found and also upper and lower bounds of the eigenvalues can be obtained.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.88-88
• /
• 2011

수자원에서 일강수량 모의기법은 다양한 목적으로 활용되고 있으며 기본적으로 수공구조물 설계 및 수자원계획을 수립하기 위한 입력 자료로서 이용된다. 수자원계획은 장기적인 목적을 가지고 수행되는 것이 일반적이며 우리가 목표로 하는 장기간의 일강수량자료의 획득이 어렵기 때문에 단기간의 일강수량자료를 장기 모의하여 이용하게 된다. 일강수량을 모의하는데 있어서 강수계열의 단기간의 기억(memory)을 활용한 Markov Chain 모형이 가장 일반적이며, 기존 Markov Chain 모형을 통한 일강수량 모의에서 발생하는 가장 큰 문제점은 극치강수량을 재현하기 어렵다는 점이다. 이러한 문제점으로 인해 수자원 계획을 수립하는데 있어서 불확실성을 가중시키고 있다. 특히 일강수량 모의기법을 통해서 추정되는 빈도강수량의 과소추정으로 인해 수공구조물 설계 시에 신뢰성을 확보하는 데 문제점이 있다. 이러한 점에서 본 연구에서는 기존 Markov Chain 모형에서 일강수량에 평균적인 특성과 극치특성을 동시에 재현할 수 있도록 불연속 Kernel-Pareto Distribution 기반에 일강수량모의기법을 개발하였다. 한강유역의 3개 강수지점에 대해서 기존 Markov Chain 모형과 본 연구에서 제안한 방법을 적용한 결과 여름의 일강수량 모의 시 1차모멘트인 평균과 2-3차 모멘트 모두 효과적으로 재현하지 못하는 문제점이 나타났다. 그러나 본 연구에서 제안한 불연속 Kernel-Pareto 분포형 기반 Markov Chain 모형은 여름의 일강수량 모의 시 강수계열의 평균적인 특성뿐만 아니라 표준편차 및 왜곡도의 경우에도 관측치의 통계특성을 매우 효과적으로 재현하는 것으로 나타났다. 본 연구에서 제시한 방법론은 전체적으로 기존 Markov Chain 모형에 비해 극치강수량을 재현하는데 유리한 기법으로 판단되며, 또한 극치강수량을 일반강수량으로부터 분리하여 모의함으로서 평균 및 중간값 등 낮은 차수에 모멘트 등 일강수량에 전체적인 분포특성을 더욱 효과적으로 모의할 수 장점을 확인하였다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.503-503
• /
• 2023

Hwang(2022; J.KWRA, 55, 10)은 수심 적분 모형으로 불연속 지형을 경사로 완화하지 않고 직접 해석하는 Hwang(2015; J.KSCE, 35, 6)의 기법이 적용된 수치 모형의 정확도를 높이기 위해 지형 전면에 실제로 작용하는 정수압 분포와 차이를 해명하는 흐름률 보정 계수(flux correction coefficient)를 도입하였다. 직각 광정 위어 실험 중에서 널리 알려진 다섯 가지 월류 실험으로부터 218회의 시행을 추려 실험과 모의에서 월류량 값이 서로 잘 일치하는 흐름률 보정 계수를 각각 산정하였는데, 이때 광정 위어를 지나는 흐름을 모의하기 위해 계산 영역을 평면 2차원으로 두고 삼각형 계산 격자로 분할하였다(Hwang, 2022). 실험에 사용된 실험 수로들이 수로의 길이 방향으로 그 폭이 일정하므로 옆벽의 영향이 크지 않다면 수로의 단위 폭에 모형을 적용함으로써 계산 영역의 차원을 한 수준 낮출 수 있다. 실질적으로 1차원 모의가 되어 모의 시간을 획기적으로 줄일 수 있으므로 다양한 분석이 가능하겠으나, 2차원 모의로부터 결정된 흐름률 보정 계수를 수정없이 그대로 적용하는 것이 적절한지 검토할 필요가 있다. 이 연구에서는 Hwang(2022)이 검토한 218회의 직각 광정 위어 실험 시행에 수로의 단위 폭에 불연속 지형을 직접 해석할 수 있는 Hwang(2015)의 1차원 모형을 적용하고 모의와 실험에서 월류량의 차이가 최소가 되는 흐름률 보정 계수를 각각 산정하였다. 결정된 흐름률 보정 계수의 평균값을 별도로 선정된 두 가지 직각 광정 위어 실험에 적용하였으며, 보정에 따른 모형의 성능을 평가하기 위해 Willmott의 일치 지표(index of agreement)를 이용하였다. 흐름률 보정 계수를 적용하였을 때, 한 실험 경우에 대해 모형의 성능이 대폭 개선됨을 확인하였고 성능 개선이 미미한 나머지 실험 경우는 보정 전에 일치 지표가 이미 상당히 높은 편이었다. 2차원 문제에 이어 1차원 모형의 적용에서도 흐름률 보정 계수를 결정함으로써 계단이나 직립 보와 같은 불연속 지형을 넘나드는 천수 흐름의 월류량을 더 쉽고 정확하게 파악할 수 있을 것으로 기대된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2022.05a
• /
• pp.147-149
• /
• 2022

This paper proposes a state machine design methodology in which an interactive robot that mimics discrete trial training (DTT protocol) can support social interaction training for children with autism. The robot applied to social interaction training uses the response to the provided training stimulus as a quantitative indicator by processing the data received from the sensors measuring the behavioral response of the child. In this process, the state machine is used as information that classifies the state of the acquired data and provides the subsequent stimulus for DTT protocol. Through the joint attentional training, it can be used as evidence-based treatment information by quantitatively classifying the data on the number of sustainable and DTT protocol and the child's response, as well as the current reaction status of the child to the observer performing remote monitoring. At the same time, it was confirmed that it is possible to properly respond to misrecognition situations.

• Journal of the Korean association of regional geographers
• /
• v.11 no.2
• /
• pp.155-168
• /
• 2005

This study gropes for historical geographic approach to regional research in view of new regional geography. A geographical methodology in regional geography pursues the dialectics of concrete totalities. Regional researches think that social processes interact with the uniqueness of regional characteristics and that region is a historical unit which changes dynamically. Time in regional changes is understood in terms of a dialectics of continuity and break. Transition from feudalism to capitalism is the important period which is captured continuity and break simultaneously. Research objects in this research are money, market and city. Money symbolizes transition to capitalism, and market and city have the importance in transition from feudalism to capitalism In Korea, historical geographic approach to money, market and city both in the era of opening ports and in the Japanese colonial times in Korea are important objects in regional geography. Colonial urban research in view of money and market from the era of opening ports to the Japanese colonial times in Korea is a theme which includes a dialectic of concrete totalities in historical geographic approach in regional geography.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.7
• /
• pp.1240-1246
• /
• 2000

The finite-difference time-domain (FDTD) method is applied to analyze a single step microstrip discontinuity in the substrate, and an equivalent circuit model comprised of two inductors and a capacitor has been developed using the numerical results. The microstrip discontinuity newly introduced in this paper has a thickness change of the substrate in the longitudinal direction with a uniform strip width. The discontinuity can be applied to the feeding circuit design for the patch antennas and interconnections between microwave circuit modules. The simulation results are compared with those computed by HFSS, and two results showed a good agreement. An equivalent circuit developed from the FDTD results, which is accurate within 2.4% in magnitudes of $S_{11}$ and $S_{21}$,can be applied for the computer-aided design of microwave circuits.

• The Journal of the Korea Contents Association
• /
• v.13 no.3
• /
• pp.428-434
• /
• 2013

With the increase of the frequency in large-scale floods and natural disasters, the demands for highly accurate numerical river models are also rapidly growing. Generally, flows in rivers are modeled with previously developed and well-established numerical models based on shallow water equations. However, the so-far-developed models reveal a lot of limitations in the analysis of discontinuous flow or flow which needs accurate modeling. In this study, the numerical shallow water model based on the discontinuous Galerkin method was applied to the simulation of one-dimensional transcritical flow, including dam break flows and a flow over a hump. The favorable agreement was observed between numerical solutions and analytical solutions.

• Journal of Advanced Navigation Technology
• /
• v.7 no.2
• /
• pp.180-190
• /
• 2003

By using accurate closed-form Green's functions obtained from real-axis integration method, the full-wave analysis of CPW discontinuities are performed in space domain. In solving MPIE(Mixed Potential Integral Equation), Galerkin's scheme is employed with the linear basis functions on the triangular elements in air-dielectric boundary. In the singular integral arising when the observation point and source point coincides, the surface integral is transformed into the line integral and the integral is evaluated by regular integration. By using the Green's function from the real-axis integration method, the discontinuities are characterized accurately.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.17 no.5
• /
• pp.460-471
• /
• 1992

By setting a new model to describe the time-discontinuous operation of PLL loop which used tri-state and sample-hold method, the stability analysis of nonlinear PLL has been performed in z-domain and the state equations for the transient response has been introduced. Until now, the lin-ear analysis by approximation of time-discontinuous to time-continuous operation had not found then stable region of time-discontinuous digital PLL exactly. However, the analysis In z-domain by the new model has been found the unstable region where the time-continuous analysis had have not. 1'herefore the limit of loop coefficient has been computed to design digital PLL optimally.

• Tunnel and Underground Space
• /
• v.9 no.2
• /
• pp.149-157
• /
• 1999

A powerful numerical method that can be used for that purpose is the Discontinuous Deformation Analysis (DDA) method developed by Shi in 1988. In this method, rock masses are treated as systems of finite and deformable blocks. Large rock mass deformations and block movements are allowed. Although various extensions of the DDA method have been proposed in the literature, the method is not capable of modeling water-block interaction that is needed when modeling surface or underground excavation in fractured rock. This paper presents a new extension to the DDA method. The extension consists of hydro-mechanical coupling between rock blocks and water flow in fractures. A example of application of the DDA method with the new extension is presented. The results of the present study indicate that fracture flow could have a destabilizing effect on the tunnel stability.